JPS585860B2 - Method for manufacturing acid-resistant cement - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for producing acid-resistant cement that can be used as various structural materials, joint materials, lining materials, etc., and exhibits excellent physical properties such as durability against acids and strength. .

Hardened cement such as Portland cement or mixed cement, which is widely used in building structures due to its excellent physical properties such as mechanical strength, workability, and economic efficiency, is a cement hydrate that is soluble in acids. Since it is mainly composed of calcium salts, it has low resistance to acids, and even alumina cement, which has relatively strong resistance, shows almost no resistance to acid solutions with a pH of 4 or less.

Therefore, these ordinary cements cannot be used in places where acid resistance is required, so much research has been done, and various so-called acid-resistant materials have now been developed.

However, as these materials improve in physical properties such as strength as well as acid resistance, they become considerably more expensive. The reality is that none of these methods has been able to provide acid-resistant cement that is fully satisfactory for practical use.

In other words, there seems to be no material that satisfies the requirements of being acid resistant, having high strength, being durable, usable for a long period of time, and being reasonably priced.

From this point of view, the purpose of the present invention is to utilize alkali silicate, which has been conventionally used in alkali silicate acid-resistant cement, as a binder, and to make use of its excellent properties such as acid resistance and heat resistance. It is an object of the present invention to provide an alkali silicate-based acid-resistant cement that further improves durability including properties, strength development, etc., is easy to construct, and is versatile and can be used at a low price.

That is, the present invention provides an acid-resistant cement containing an alkali silicate as the binder, in which part or all of the binder is applied to the surface of solid particles such as silica, quartz, or porcelain, and these solid particles and an alkali silicate solution are thoroughly mixed. The first advantage is to form a film by post-drying and use it as an aggregate, a filler, or a composite binder containing aggregate, and further add hardening accelerators such as silicates, phosphates, and alumina. This method of producing acid-resistant cement is characterized by mixing one or more of cement, a mixture of silicone varnish, etc., and additives.

Alkaline silicate compounds, especially sodium silicate, have been widely used as a cheaper inorganic binder in various applications such as injection grouting materials and adhesives. It is already known that an alkali silicate acid-resistant cement can be obtained by combining a curing accelerator, additives such as zinc oxide and alumina cement, and a mixture.

These currently reported acid-resistant cements include silica,
When used, a powder containing aggregates or fillers such as quartz or porcelain, hardening accelerators such as sodium silicate and condensed aluminum phosphate, and alumina cement are mixed with a sodium silicate solution as a binder. do 2
There is a package type and a single package type that uses powdered sodium silicate as a binder and can be used by simply kneading it with water.By changing the curing accelerator etc., acid resistance, water resistance, strength, etc. can be improved. A variety of cements with different values have been obtained.

However, with these conventional methods, it is almost impossible to satisfy all the properties required for acid-resistant cement.

That is, in order to improve water resistance, metal oxides such as zinc must be added, and as a result, acid resistance, which is the most important, decreases.

Furthermore, if the particles of aggregate or filler are made smaller in order to improve strength and durability, or if the amount of sodium silicate is increased, the drawback is that the drying shrinkage of the cured product increases. .

Therefore, it is mostly used as a joint or lining material for acid-resistant bricks and tiles, and it has yet to be used as a structural material or in places where strength is required with the same reliability as Portland cement. The reality is that there is none.

Therefore, the inventor of the present invention aimed to create an all-purpose acid-resistant cement that is not only acid-resistant but also excellent in all aspects such as water resistance, durability, and workability.As a result of various experimental studies, the inventor simply added the necessary ingredients as described above. In addition to the method of simply mixing, some or all of the alkaline silicate solution used as a binder is applied to the surface of solid particles such as silica, quartz, and porcelain, which are usually used in large quantities as aggregates or fillers, preferably solid particles 10
0 parts to 5 to 25 parts (in terms of solid content) are sufficiently mixed with solid particles and dried to form a solid alkali silicate film on the surface of the solid particles, which can be used as aggregate, filler, or bone. By using this material as a composite binder containing the same material, we succeeded in obtaining acid-resistant cement that has good physical properties not only in strength and durability but also in other aspects.

That is, according to the method of the present invention, firstly, the present cement has an alkali silicate film formed on the surface of the solid particles in advance, and furthermore, a strong bond is formed between the alkali silicate and the solid particles. Second, when kneaded with water, a part of these surface coatings dissolves and can serve as the binder or a part of the binder. Therefore, in the case of ordinary acid-resistant cement, it is possible to Alternatively, powdered alkali silicate dissolved in water must bond solid particles together, whereas the acid-resistant cement of this method does not bond aggregate to aggregate, but firmly adheres to aggregate. It is sufficient to perform bonding between alkali silicates.

Therefore, the unbonded parts due to voids between solid particles are reduced, and the structure of the cured product becomes dense, resulting in a cement with good strength and durability.

Furthermore, according to this method, compared to conventional acid-resistant cement manufactured by simply mixing the necessary materials, it is possible to reduce the amount of mixing water required to obtain the same level of fluidity by approximately 2%, resulting in the same fluidity. In the sample, a denser cured product was obtained, and the strength, durability, and other physical properties were further improved.

The reason for this is that the surface of the aggregate and filler is covered with an alkali silicate layer, so a large amount of water mixed during kneading is not used to wet the surface of the aggregate and filler, but is mainly used for bonding. Alkali silicate and curing accelerator necessary for
This is because it is used only for dissolution bonding reactions of other mixed materials.

In the present invention, an alkali aluminate, for example, sodium aluminate, is added to the alkali silicate solution as a binder so that the Al content is o. i~3
．． It can be used as an acid-resistant cement by dissolving it to a concentration of 0 mol%, preferably 0.8 to 2.0 mol%, for film formation, and drying it as a powdered alkali silicate for mixing. The strength and durability of the steel can be further improved.

That is, by adding A7, in addition to -S i -0-S i -@, which exists in the alkali silicate, -S
An i-0-AA bond is formed, which increases the bonding force of the polymerization of silicate ions during the bond-hardening reaction, and also reduces the solubility of monosilicate ions in the solution. This is thought to result from improvements in durability, etc.

To explain this in an easy-to-understand manner, alkali silicate is a type of glass, as can be seen from the fact that it is usually called water glass. This can be understood from the well-known fact that the water resistance etc. of

There is an appropriate range for the amount of aluminum added; if it is too little, no effect will be recognized, and if it is too much, it will be AA.
This is because the atoms do not form 4-position bonds like Si atoms, but instead form 6-position bonds, which rather has a detrimental effect on the bonding reaction, such as causing gelation of the alkali silicate.

Various types of alkali silicate are commercially available to be used as a binder in the present invention, and although there are no particular limitations, the cheapest sodium silicate is usually sufficient, and it has good curing time, acid resistance, and other physical properties. When considered comprehensively, No. 2 sodium silicate is generally preferred.

Further, as curing accelerators for alkali silicate, there are generally silicate, condensed aluminum phosphate, various phosphates, etc., and any of them can be used, but sodium fluorosilicide is usually sufficient.

Sodium silicofluoride (Na2S i
The curing reaction when using F6) is as follows.

2Na20 5Si02+〇. 5Na2SiF64Na
20.4Si02+15SiO2+3NaFAs shown in the above equation, when the molar ratio of Si02 and Na20 in sodium silicate becomes 4 or more, the viscosity of the alkaline silicate solution increases rapidly and solidifies.

In fact, the amount of the curing accelerator Na2SiF6 to be added is preferably 1.2 to 1.5 times the amount required for the above reaction.

In the cement of the present invention, a better cement can be obtained by adding materials such as silicon face as an additive and alumina cement as a mixed material.

In this case, silicon face is 0.5% by weight based on cement.
It is desirable to premix the resin with sodium fluorosilicide, which is a curing accelerator.

This is because it has the effect of covering the surface of sodium silicate and suppressing its reactivity.

Other examples of such additives that can be used include silicone oil, paraffin, and other animal and vegetable oils.

Alumina cement is mixed with the intention of further densifying the hardened cement with the product during hydration and preventing the penetration of acid solutions, etc. However, if the amount of the mixture is too large, it will become acid resistant. Therefore, the mixing amount is naturally limited, and the desired effect can usually be obtained with an amount of about 15% by weight or less.

Other soluble aluminates added to alkali silicate include sodium aluminate and potassium aluminate.
Although either can be used, sodium arsinate, which is the cheapest, is usually sufficient.

In addition, solid particles for surface coating with a binder as an aggregate or filler are not limited to the aforementioned silica, quartz, porcelain, etc., but preferably have silanol groups (-Si-OH) on the surface of the solid particles. It is more preferable to use a material that has a chemical bond with the silicate ion in the alkali silicate, and silica is an inexpensive and easily available material. I can recommend it.

The preparation of these raw materials D and the method for producing cement are as shown in D below.

First, silica stone as an aggregate or filler is crushed using a crusher, top glider, or ball mill to a predetermined particle size of, for example, 1.5 mm or less. 10 to 100 parts, preferably 20 to 40 parts of acid soda solution are mixed.

Note that for trenches containing sodium aluminate, a predetermined amount of sodium aluminate dissolved in a sodium silicate solution is used. It is also possible to mix the silica with the silica stone and then with the sodium silicate solution; however, the latter may be more desirable in terms of ease of mixing.

This silica monosilicate sodium solution mixture is then dried and granulated so that the water content of the alkali silicate is approximately 20% by weight or less.

In this case, spray drying is preferable for drying, but it may also be dried in a box-type dryer or the like and then re-pulverized in a crusher or the like to an extent that the sodium silicate coating is not damaged.

In the production of cement, furthermore, to 100 parts of this dried silica monosilicate mixed product, 0 to 30 parts of powdered sodium silicate and 100 parts of sodium silicate (anhydrous equivalent) of sodium silicate as a hardening accelerator are added. ) to 20 to 40 parts of silicone varnish as an additive to 1 part of soda silica
The acid-resistant cement of the present invention is prepared by adding 0 to 20 parts, preferably 5 to 15 parts to 00 parts, and 25 parts or less, preferably 7 to 18 parts, of alumina cement as a mixing material to 100 parts of the above mixture. be.

Note that it is better to mix the soda silicate as a hardening accelerator and the silicone varnish as an additive before mixing them into the cement, and to cover the surface of the soda silicate with a silicone varnish film to reduce the curing reaction time of the cement. More preferable results can be obtained in terms of delay in oxidation, fluidity of cement, etc.

The cement produced in this way is prepared by adding an appropriate amount of water, usually 1
It is suitable for on-site construction because it hardens at room temperature by adding 2 to 18% by weight of water and kneading it.

That is, it can be constructed into any desired shape at the site by any construction method such as pouring, brushing, or spraying after adding water and kneading at the time of use.

Next, the present invention will be explained in more detail by way of examples along with comparative examples.

Example l 30 parts of No. 2 sodium silicate solution (solid content 49%) was mixed with 100 parts of 1410μ silica stone crushed to about 1% or less, and the mixture was spread thinly on a polypropylene plate. 100-15 until it becomes about 52% of the weight of
Dry at 0°C, lightly loosen the adhering particles with sodium silicate, and form a mixed film formed by sodium silicate (
Hereinafter referred to as a mixed dry product) was obtained.

Next, to 84 parts of this mixed dry material, powdered sodium silicate (JIS standard No. 2 sodium silicate solution was added to 52% of the original weight).
After drying until the mixture was dried, 16 parts of pulverized to 500 μm or less), 7.5 parts of sodium silica, and 0.5 parts of silicone varnish (TSR 44, manufactured by Toshiba Silicon Co., Ltd.) were kneaded to obtain an acid-resistant cement.

In addition, when mixing, a method was adopted in which soda silica and silicone varnish were mixed in advance and then mixed with other samples.

Example 2 7.5 parts of commercially available alumina cement was further mixed with 92.5 parts of the material prepared in Example 1 to obtain acid-resistant cement.

Example 3 After mixing 0.18 parts of sodium alumino acid with 100 parts of silica stone having the same particle size as that used in Example 1, which was crushed to 1410μ remaining about 1% or less, No. 2 silicic acid was added to this mixture. Example 1 Mixed with 30 parts of soda solution
The aluminum content was treated in the same manner as Sl in sodium silicate.
A dried mixed product of a sodium silicate composition containing approximately 1.3 mol % based on the amount was obtained.

Next, 84 parts of this mixed dry product was added with powdered sodium silicate (2
For the Si content in the sodium silicate solution,
Addition and dissolution of sodium aluminate corresponding to 1.3 mol% of A7, dried to 52% of the original weight, and then ground to less than 500μ) 16 parts, 7.5 parts of sodium silica, 5 parts of silicone varnish O was mixed in the same manner as in Example 1 to obtain an acid-resistant cement sample.

Example 4 To 92.5 parts of the sample prepared in Example 3, 7.5 parts of alumina cement was further added and mixed to obtain acid-resistant cement.

Example 5 To 90 parts of the sample prepared in Example 3, 10 parts of alumina cement was further added and mixed to obtain acid-resistant cement.

Example 6 After mixing and dissolving 0.36 parts of sodium aluminate dissolved in 20 parts of water in 60 parts of No. 2 sodium silicate solution, 100 parts of C silica stone having the same particle size as that used in Example 1 was added. The mixture was pre-dried using a spray dryer, and then the degree of drying was adjusted using a box dryer to obtain a dried mixed product.

Next, 7 parts of sodium silica was added to 100 parts of this dry sample.
．． 5 parts of silicone varnish and 0.5 parts of silicone varnish were mixed in a method using a pre-mixed mixture of sodium silicate and silicone varnish to obtain an acid-resistant cement sample.

In this case, the amount of sodium aluminate added was 1.3 mol % based on the Sl content in the sodium silicate.

Furthermore, additional drying using a box-type dryer was carried out with the intention of keeping the degree of drying (water content) of the sodium silicate at the same level for comparison with the physical properties of cement according to Examples 1 and 3; Drying using only a spray dryer (water content of sodium silicate is about 15%) is sufficient.

Comparative Example 1 Same as Example 1, 15.6 parts of powdered sodium silicate equivalent to 30 parts of dry No. 2 sodium silicate solution was mixed with 100 parts of silica stone crushed to about 1% of 1410μ residue. A mixed product corresponding to the dried mixed product was obtained.

Next, 16 parts of powdered sodium silicate was added to 84 parts of this mixture.
parts, 7.5 parts of sodium silica, 0.5 parts of silicone varnish
were mixed in the same manner as in Example 1 to obtain a comparative cement sample.

Comparative Example 2 7.5 parts of commercially available alumina cement was mixed with 92.5 parts of the comparative cement sample prepared in Comparative Example 1 to obtain a comparative cement sample.

In Examples 1 and 2 and Comparative Examples, powdered sodium silicate prepared in the laboratory was used, but this was done with the intention of conducting studies under the same conditions. Therefore, in actual production, there is no problem even if commercially available powdered sodium silicate is used.

In addition, in the examples, the particle size of the solid particles used was 1410 μm.
Although only the case where the residual content is about 1% or less is shown, the particle size is not limited to this in any way, and particles of any particle size may be used.

In general, the effect of particle size is that if the amount of kneading water is constant, the fluidity will be better if a particle with a larger particle size is used.
Although the drying shrinkage of the cured product is reduced, there is a tendency for the strength to decrease to some extent.

Note that the drying shrinkage of the cured product obtained by adding 12 to 14% water to the cement shown in the examples and kneading the mixture is about 0.03 to 0.3%.

Next, Table 1 shows examples of physical tests such as strength on the cement produced as described above, and Table 2 shows examples of water and acid resistance tests.

The preparation and testing methods for test specimens are as follows.

(Preparation of test specimens) Using cement samples manufactured by the method shown in the examples and comparative examples, a predetermined amount of water was added and kneaded, and then placed in a mold to form a 4 x 4 x 16 cm test specimen. After producing and curing in a humid air for 7 days, it was used as a sample for strength measurement and other physical property measurements.

In addition, a Hobart mixer of the same type as that specified in ASTM-C305 was used in the cement mixing field, and 1800 g of cement was weighed into a mixing bowl, and after adding a predetermined amount of water, the mixer was initially rotated at 140 rpm. 60 seconds, then 2
The mixture was kneaded at 85 rpm for 90 seconds, then paused for 30 seconds, during which time the materials adhering to the kneading bowl and paddles were scraped off, and then kneaded at 285 rpm for 60 seconds.

(Measurement of flow value and pot life) The flow value of the cement mortar adjusted according to the method described above was measured and used as an index of fluidity. Tested accordingly.

Further, the pot life is defined as the time when the flow value reaches 105 m after kneading.

(Water resistance, acid resistance test) Water resistance and acid resistance tests were conducted using water, 2% sulfuric acid, 2% hydrochloric acid, and 50% sulfuric acid, respectively, after kneading and curing in a moist air for 7 days.
After being immersed in a ℃ solution for a predetermined period of time, strength, weight changes, etc. were tested.

As can be seen from the test results shown in Tables 1 and 2 above, the cement of the present invention is more effective than the cement of the present invention as compared to the cement produced by the usual manufacturing method of simply mixing the necessary components. According to the method set forth in claim 1, a cement excellent in terms of strength development, water resistance, acid resistance, etc. can be obtained, and according to the method set forth in claim 2, a cement having even better physical properties can be obtained. It is clear that this can be obtained.

Furthermore, in terms of heat resistance, the cured product of the cement of the present invention shown in the Examples has a strength of 250 kgf/cm' or more even when fired at 800°C for 3 hours, and the kneading change rate is -0. It exhibits excellent physical properties with a content of 5% or less.

Claims (1)

[Scope of Claims] 1. In an acid-resistant cement using an alkali silicate as a binder, a part or the entire amount of the binder is applied to the surface of solid particles such as silica, quartz, porcelain, etc., and these solid particles and an alkali silicate solution are sufficiently mixed. It is characterized by forming a film by mixing and drying, and using it as an aggregate, a filler, or a composite binder containing aggregate, and a hardening accelerator such as a silicate or phosphate, and alumina cement, A method for producing acid-resistant cement by mixing one or more of mixed materials such as silicone fest, additives, etc. 2. Soluble aluminates such as sodium aluminate and potassium aluminate are added to the alkali silicate used in the method for producing acid-resistant cement in item 1, and the Al content is 0.1 to 3. A method for producing acid-resistant cement, which comprises mixing and dissolving or solid-dissolving the cement so that the molar ratio is 0.